:root{--primary-color: #1a73e8;--bg-color: #f8f9fa;--sidebar-bg: #ffffff;--text-color: #3c4043;--border-color: #dadce0}body{margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;background-color:var(--bg-color);color:var(--text-color)}.app-container{display:flex;min-height:100vh}.sidebar{width:250px;background:var(--sidebar-bg);border-right:1px solid var(--border-color);display:flex;flex-direction:column}.main-content{flex:1;display:flex;flex-direction:column}.header{height:60px;background:#fff;border-bottom:1px solid var(--border-color);display:flex;align-items:center;padding:0 20px;justify-content:space-between}.content-area{padding:20px;overflow-y:auto}nav ul{list-style:none;padding:0}nav li a{display:block;padding:15px 20px;text-decoration:none;color:var(--text-color)}nav li a:hover{background:#f1f3f4}.card{background:#fff;border-radius:8px;box-shadow:0 1px 3px #0000001a;padding:20px;margin-bottom:20px}